Main drain no suction-normal?

[40galpool]

I'm a nebie so don't laugh.

1) I have a 40 gallon in ground rectangle pool with 2 skimmers and 2 jets plus a main drain in deep end. I noticed the main drain did not have any suction. The sand pump was on filter mode when I checked the main drain. Is this normal to have no suction?

2) After adding chemical(s) to pool (ie algacide, liquid chlorine, etc.), do I operate the pump on filter or recirculate?

[Backglass]

I have a 40 gallon in ground rectangle pool

Weeeeeeeeee wish to welcome you to Munchkin Laaaaaaand!

OK...sorry...I could't resist. You certainly do have a tiny pool.

I noticed the main drain did not have any suction. The sand pump was on filter mode when I checked the main drain. Is this normal to have no suction?

If you have multiple suction lines (skimmers, main drains, etc) you will have valves somewhere that you can change to decide which to "suck from".

After adding chemical(s) to pool (ie algacide, liquid chlorine, etc.), do I operate the pump on filter or recirculate?

Filter is fine.